1. Field of the Invention
The invention relates to a combustion chamber, in particular to one in a gas turbine, having at least two burners that are connected to a fuel supply via controllable fuel valves.
2. Brief Description of the Related Art
Gas turbines are used, for example, for the generation of electrical energy in power plants, where they drive generators. Such turbines usually have a power of more than 50 MW and are designed, in particular, for stationary continuous operation. In order to be able to operate the gas turbine economically and with low pollutant emissions, in particular NOx, the aim should be to operate it in a lean fashion, that is to say with as little fuel as possible, and, on the other hand, to avoid extinguishing the burner, since restarting the gas turbine is complicated and expensive.
However, this can give rise to a conflict of aims, since it is possible, particularly in the case of a lean operation of the gas turbine, for the flame in the combustion chamber to pulsate, and this leads to extinction of the same in the most unfavorable case. Pulsation of the flame depends in this case on various parameters such as, for example, an air volumetric flow and a fuel volumetric flow associated therewith, as well as on a fuel chamber temperature. Fundamentally, what is desired for the burners or the combustion chamber is a flame system that can be designated as stable, and in the case of which a quasi-stationary pulsation-free ignition zone is formed in the vicinity of the burner outlet that, apart from turbulence-induced stochastic positional fluctuations, burns at a fixed location even in the event of slight fluctuations in the entry flows.
For the purpose of being able to prevent pulsation of the flame in the combustion chamber, and thereby possible extinction of the flame, it is important to detect pulsation-prone burners as early as possible and to take appropriate countermeasures, since, as mentioned above, restarting the gas turbine because of an extinction of the flame is very complicated and expensive, and the economic efficiency of the gas turbine is negatively influenced thereby. Moreover, pulsating burners also diminish the efficiency of the gas turbine such that it should also be ensured with regard to a power yield that the quasi-stationary, pulsation-free ignition zone be formed in the region of the vicinity of the burner outlet.